She said that she didn’t know what (had) happened. / The rewards are greater than the difficulties.
1.
“She said that she didn’t know what happened.”
→Is this sentence correct? How about “what HAD happened”? Which do you prefer? Why?

2.
“The rewards are greater than the difficulties.”
→Can I write this sentence in this way? - “The rewards are greater than the difficulties are.” Which do you prefer?

By the way, here is my eariler question, but it didn't receive an answer, so I hope anyone can help me with it.
https://www.italki.com/question/356638

Thanks!

Question

She said that she didn’t know what (had) happened. / The rewards are greater than the difficulties.
1.
“She said that she didn’t know what happened.”
→Is this sentence correct? How about “what HAD happened”?  Which do you prefer? Why?

2.
 “The rewards are greater than the difficulties.”
→Can I write this sentence in this way? - “The rewards are greater than the difficulties are.” Which do you prefer?

By the way, here is my eariler question, but it didn't receive an answer, so I hope anyone can help me with it.
https://www.italki.com/question/356638

Thanks!

Answer

1. Both are correct. It's a matter of preference which you choose to say. However, in professional or academic writing, you'd want to use the word "had". It just looks more polished that way. In everyday speaking or writing, I'd usually leave the "had" out.

2. Both are correct. Again, adding the extra "are" at the end makes it sound more formal and polished. I would very rarely add it, though. It's mostly superfluous.

Answer

1. Either is possible. If everything is in the past and the sequence is unimportant, then the simple past is, well, simpler. If it is important to place the happening before the saying, then use the pluperfect.
2. Either is correct grammatically, but the original is unambiguous, shorter and more natural.

Answer

1. She said she didn't know what had happened ... I prefer it because I expected something had happened before she knew it.
2. Rewards are greater than difficulties ... I would not use THE because no one know what rewards and difficulties are.

Note: I'm not an English native speaker. I'm, also, practicing my English. So, my answer mightn't correct.